The invention relates to a method of determining the position of a wanted object which is positioned in a row of objects, said objects being each provided with a transponder.
The invention also relates to a system for determining the position of a wanted object which is positioned in a row of objects, said objects being each provided with a transponder.
Such a method and such a system are known from the patent document U.S. Pat. No. 5,936,527 A. A method and a system for determining the position of a wanted object are known from the patent document U.S. Pat. No. 5,936,527 A, according to which the position of a wanted object can only be determined as being within a given shelf or within a given drawer. This means that it is indeed possible to determine exactly the shelf carrying the wanted object from among a plurality of shelves or the drawer containing the wanted object from among a plurality of drawers for finding a wanted object, but that subsequently the wanted object is to be individually located on the determined shelf or in the determined drawer by means of a manually performed search, which represents an additional, undesirable effort. Because of this fact, an automatic removal of a wanted object from the determined shelf or drawer is not possible either.
The invention has for its object to eliminate the limitations described above and to provide an improved method and an improved system.
To achieve the object mentioned above, according to the invention, a method as mentioned in the opening paragraph is characterized in that a left scanning signal for triggering a response signal of a transponder, with which the wanted object is fitted, is supplied with a left current strength having a starting value to a left transmission coil which is provided at a left-hand end of the row of objects, and in that subsequently the left scanning signal for triggering the response signal of the transponder, with which the wanted object is fitted, is supplied to the left transmission coil with left current strengths changed in steps, such that a change in accordance with a minimum current value difference is carried out upon changing of the left current strength, and in that it is ascertained for each step whether the transponder, with which the wanted object is fitted, has given off the response signal triggered by means of the left scanning signal supplied to the left transmission coil, and in that the value is determined of that changed left current strength of the left scanning signal with which after a change of the left current strength in accordance with the minimum current value difference the left scanning signal was supplied to the left transmission coil, and in that a right scanning signal for triggering the response signal from the transponder, with which the wanted object is fitted, is supplied in a first step to a right transmission coil, which is provided at a right-hand end of the row of objects, with a right current strength having a starting value, and in that subsequently the right scanning signal for triggering the response signal of the transponder, with which the wanted object is fitted, is supplied to the right transmission coil with right current strengths changed in steps, such that a change in accordance with a minimum current value difference is carried out upon changing of the right current strength, and in that it is ascertained for each step whether the transponder, with which the wanted object is fitted, has given off the response signal triggered by means of the right scanning signal supplied to the right transmission coil, and in that the value is determined of that changed right current strength of the right scanning signal with which after a change in the right current strength in accordance with the minimum current value difference the right scanning signal was supplied to the right transmission coil, and in that the position of the wanted object is determined from the knowledge of said value of the determined changed left current strength of the left scanning signal and from the knowledge of said value of the determined changed right current strength of the right scanning signal.
To achieve the object as mentioned above, according to the invention, a system as mentioned in the second paragraph is furthermore characterized in that a left transmission coil is provided which is arranged at a left-hand end of the row of objects, and in that left scanning signal generation means are provided by means of which a left scanning signal for triggering a response signal of a transponder, with which the wanted object is fitted, can be supplied in a first step to the left transmission coil with a left current strength having a starting value, and by means of which subsequently the left scanning signal can be supplied to the left transmission coil with current strengths changed in steps, and by means of which a change in the left current strength in accordance with a minimum current value difference is achievable, and in that left detection means are provided by means of which it can be ascertained whether the transponder, with which the wanted object is fitted, has given off the response signal triggered by means of the left scanning signal supplied to the left transmission coil, and in that left current strength value detection means are provided by means of which the value can be determined of that changed left current strength of the left scanning signal with which after a change in the left current strength in accordance with the minimum current value difference the left scanning signal was supplied to the left transmission coil, and in that a right transmission coil is provided which is arranged at a right-hand end of the row of objects, and in that right scanning signal generation means are provided by means of which the right scanning signal for triggering the response signal of the transponder, with which the wanted object is fitted, can be supplied in a first step to the right transmission coil with a right current strength having a starting value, and by means of which subsequently the right scanning signal can be supplied to the right transmission coil with current strengths changed in steps, and by means of which a change in the right current strength in accordance with a minimum current value difference is achievable, and in that right detection means are provided by means of which it can be ascertained whether the transponder, with which the wanted object is fitted, has given off the response signal triggered by means of the right scanning signal supplied to the right transmission coil, and in that right current strength value detection means are provided by means of which the value can be determined of that changed right current strength of the right scanning signal with which after a change in the right current strength in accordance with the minimum current value difference the right scanning signal was supplied to the right transmission coil, and in that position determination means are provided by means of which the position of the wanted object can be determined from the knowledge of said value of the determined changed left current strength of the left scanning signal and from the knowledge of said value of the determined changed right current strength of the right scanning signal.
The provision of the measures according to the invention renders it possible by comparatively simple means and with a comparatively small expenditure to determine the position of a wanted object present in a row of objects in a very accurate and reliable manner. The major advantage is achieved thereby that the storage location of a wanted object can be exactly determined automatically, so that an additional search for a wanted object in a manual search operation becomes redundant. Furthermore, an automatic removal of a wanted and found object from the row of objects is advantageously rendered possible thereby, because an automatic delivery device may be automatically displaced towards the wanted and found object after the determination of the wanted object, whereupon an automatic removal of the wanted and found object by means of the delivery device can take place. It is to be noted that the measures according to the invention appear to be highly advantageous in particular in libraries for the purpose of finding books. The measures according to the invention, however, are also highly advantageous in other areas of application, for example in commercial warehouses of retail businesses, or storage shelf systems in factories.
In a method according to the invention and a system according to the invention, the starting value of the left current strength and the starting value of the right current strength may each be formed by a minimum value of these two current strengths. It was found to be particularly advantageous, however, if the starting value of the left current strength and the starting value of the right current strength are each formed by a maximum value, i.e. the left scanning signal is supplied with a maximum left current strength to the left transmission coil in the first step, and the right scanning signal is supplied with a maximum right current strength to the right transmission coil in the first step. It is advantageously achieved thereby that a response signal from a wanted transponder may already be counted on in each first step, which has the result that the absence of a response signal in the first step can lead to the conclusion that the wanted transponder with which the wanted object is fitted, and accordingly the wanted object itself, is not present in a row of objects.
After the left current strength and the right current strength have each been supplied to the relevant transmission coil with a maximum value in the first step, the respective current strengths may be changed in steps, for example with constantly decreasing current value differences, in the subsequent steps. It was found to be very advantageous, however, if the left current strength and the right current strength are each changed in steps of substantially the same current value difference. This was found to be advantageous for achieving a detection process which is as simple as possible.
After the left current strength and the right current strength have each been supplied with a maximum value to the relevant transmission coils in each first step, it is possible in the subsequent steps to start with a minimum value for the two current strengths and to carry out a constant, stepwise increase in the two current strengths. It was found to be very advantageous, however, if after each first step, in which the relevant current strength is supplied to the corresponding transmission coil with a maximum value, the left scanning signal is supplied to the left transmission coil with left current strengths reduced with respect to the maximum value in steps of substantially constant current value differences, and the right scanning signal is supplied to the right transmission coil with right current strengths reduced with respect to the maximum value in steps of substantially constant current value differences. This was found to be advantageous for achieving a detection of a wanted transponder, and accordingly of a wanted object, in as fast and simple a manner as possible. Advantageously, the two maximum values are chosen to be equal, but this need not necessarily be the case. Advantageously, the current value differences are equal to the minimum current value difference in all steps.
In a method according to the invention and a system according to the invention, the exact position of a wanted object can be determined on the basis of said values of the detected reduced left current strength of the left scanning signal and the detected reduced right current strength of the right scanning signal at which the transponder, with which the wanted object is fitted, has not delivered any more response signals. It was also found to be very advantageous, however, if the position of a wanted object is determined on the basis of said values of the detected reduced left current strength of the left scanning signal and the detected reduced right current strength of the right scanning signal at which the transponder, with which the wanted object is fitted, has given off the relevant response signal for the last time before the transponder for the first time has not given such a response signal any more.
In a method according to the invention, the delivery of the response signals by a transponder with which the wanted object is fitted may be ascertained by means of a separate transmission coil, which separate transmission coil is preferably arranged between the left transmission coil and the right transmission coil. It was found to be highly advantageous, however, if in a method according to the invention the delivery of the response signals by a transponder is ascertained by means of the left transmission coil and the right transmission coil which are both present anyway. This is advantageous for achieving a system for carrying out this method which is as simple as possible.
The aspects described above as well as further aspects of the invention will become apparent from the description of an embodiment given below and are clarified with reference to this embodiment.